Effects of passive heat adaptation and moderate sweatless conditioning on responses to cold and heat

Two series of experiments were performed in physically untrained subjects. In series A (heat adaptation, HA), seven male subjects were adapted to dry heat (five consecutive days at 55 degrees C ambient air temperature (Ta) for 1 h X day-1) under resting conditions. Before and after HA, the subjects' shivering responses were determined in a cold test (Ta + 10 to 0 degrees C). In series B, eight male subjects underwent mild exercise training (five consecutive days at a heart rate, HR, of 120 b X min-1) under Ta conditions individually adjusted (Ta + 15 to +5 degrees C) to prevent both sweating and cold sensations. Before and after "sweatless training", the subjects were subjected to a combined cold and heat test. During HA the thresholds for shivering, cutaneous vasodilatation (thumb and forearm) and sweating were shifted significantly (p less than 0.05) towards lower mean body temperatures (Tb). The mean decrease in threshold Tb was 0.36 degrees C. "Sweatless training" resulted in a mean increase in work rate (at HR 120 b X min-1) and oxygen pulse of 13 and 8%, respectively. However, "sweatless training" did not change the threshold Tb for shivering or sweating. Neither HA nor "sweatless training" changed the slopes of the relationships of shivering and sweating to Tb. It is concluded that the previously reported lowering of shivering and sweating threshold Tb in long-distance runners is not due to an increased fitness level, but is essentially identical with HA. The decreased shivering threshold following HA is interpreted as "cross adaptation" produced by the stressors cold and heat.     

A multinomial model for estimating the size of a whale population from incomplete census data

This paper adapts the removal method of population size estimation to the problem of estimating the size of the western Arctic stock of bowhead whales. The whales are counted during their spring migration as they pass two census camps located near Point Barrow, Alaska. Whales seen at the first camp are "removed" from the population of concern to the second camp, where only whales missed by the first camp are counted. If both camps were in operation throughout the migration and if the probability of missing a whale were constant, the removal method would provide a population size estimate based on a trinomial model in which the size of the population would be the number of trials, whales counted by each camp would provide the observed cell totals, and whales missed by both camps would represent an unobserved cell total. Since the probability of missing a whale depends on visibility, we model the population size as the sum of the number of trials of several independent trinomial distributions, each of which represents a particular visibility condition occurring during the census. To account for the fact that watch cannot be maintained at both camps throughout the migration, we derive a confidence interval estimate of the number of trials under a more general model allowing for incomplete observation of totals within particular cells as well as for completely unobserved cells.     

Aspergillus fumigatus chsE: A Gene Related to CHS3 of Saccharomyces cerevisiae and Important for Hyphal Growth and Conidiophore Development but Not Pathogenicity

The Aspergillus fumigatus chsE (AfchsE) gene was isolated from an A. fumigatus DNA library on the basis of hybridization to a segment of Saccharomyces cerevisiae CHS3 (ScCHS3). The amino acid sequence derived from AfchsE is 28% identical with ScCHS3 and 80% identical with the product of Aspergillus nidulans chsD (AnchsD). A mutant strain constructed by disruption of AfchsE has reduced levels of mycelial chitin, periodic swellings along the length of hyphae, and a block in conidiation that can be partially restored by growth in osmotic stabilizer. This phenotype is different from that reported for an AnchsD mutant, in which germinating conidia and hyphal tips undergo lysis and the colonial growth rate is significantly reduced. Despite the defects associated with the AfchsE- strain, its virulence was not significantly reduced when compared with the wild-type parental strain in a mouse model of pulmonary aspergillosis.     

ABUNDANCE AND POPULATION TREND (1978-2001) OF WESTERN ARCTIC BOWHEAD WHALES SURVEYED NEAR BARROW, ALASKA

The 2001 survey of western Arctic (Bering, Chukchi, and Beaufort seas) bowhead whales was conducted from 5 April to 7 June near Barrow, Alaska. Visual observers recorded a total of 3,295 “new” (not seen before) and 532 “conditional” (possibly seen before) whales in 1,130 h of watch effort, including 121 new calves (3.7% of the new whales). Concurrent with the visual survey, passive acoustic surveillance was conducted almost continuously from 16 April to 31 May, resulting in 27,023 locations of vocalizing bowhead whales. The estimated number of whales within 4 km of the perch (N₄) was 7,025 (SE = 1,068). The estimated proportion of the whales within 4 km of the perch (P₄) was 0.862 (SE = 0.044, computed by a moving blocks bootstrap). Combining these, the abundance estimate (N₄/P₄) for 2001 is 10,470 (SE = 1, 351) with a 95% confidence interval of 8, 100–13, 500. The estimated annual rate of increase (ROI) of the population from 1978 to 2001 is 3.4% (95% CI 1.7%‐5%). Reports from hunters and results of an aerial survey in June 2001 indicate whales continued to pass Barrow after the survey had ended. In 2001 51% (572 h) of the watch was scored as occurring during “fair‐excellent” visibility conditions, somewhat lower than the average for all surveys since 1978. Sea ice in the leads and fog were the principle environmental factors affecting visibility for all years. The estimated rate of increase and the fact that the number of calves counted in 2001 is the highest ever recorded suggest a steady recovery of this population. Other populations of large balaenids, notably the North Atlantic right whale, have failed to recover despite 70 yr of protection. The recovery of the howhead whale is likely attributable to low anthropogenic mortality, a relatively pristine habitat, and a well‐managed subsistence hunt. Nonetheless, offshore oil development, increasing shipping traffic, changes in the Bering Sea ecosystem, sea ice retreat, and possibly killer whale predation within its range could impact this bowhead population and should be carefully monitored.     

Endogenous HMGB1 regulates autophagy

Autophagy clears long-lived proteins and dysfunctional organelles and generates substrates for adenosine triphosphate production during periods of starvation and other types of cellular stress. Here we show that high mobility group box 1 (HMGB1), a chromatin-associated nuclear protein and extracellular damage-associated molecular pattern molecule, is a critical regulator of autophagy. Stimuli that enhance reactive oxygen species promote cytosolic translocation of HMGB1 and thereby enhance autophagic flux. HMGB1 directly interacts with the autophagy protein Beclin1 displacing Bcl-2. Mutation of cysteine 106 (C106), but not the vicinal C23 and C45, of HMGB1 promotes cytosolic localization and sustained autophagy. Pharmacological inhibition of HMGB1 cytoplasmic translocation by agents such as ethyl pyruvate limits starvation-induced autophagy. Moreover, the intramolecular disulfide bridge (C23/45) of HMGB1 is required for binding to Beclin1 and sustaining autophagy. Thus, endogenous HMGB1 is a critical pro-autophagic protein that enhances cell survival and limits programmed apoptotic cell death.     

Natural and newly synthesized hydroxy-1-aryl-isochromans: a class of potential antioxidants and radical scavengers

We investigated the antioxidant and radical scavenging activity of polyphenolic isochromans. To assess the relation between structure and scavenging properties the natural occurring 1-(3'-methoxy-4'-hydroxy)phenyl-6,7-dihydroxy-isochroman (ISO-3, three OH groups) was compared with three newly synthesized derivatives that differ in their degree of hydroxylation by substitution with methoxy-groups (ISO-4: four OH groups; ISO-2: two OH groups and ISO-0: fully methoxylated). We found that ISO-4 is a 2-fold better scavenger for the artificial radical 1,1-diphenyl-2-picrylhydrazyl (DPPH, 100 microM) with an EC50=10.3 microM compared to the natural ISO-3 (EC50=22.4 microM) and to ISO-2 (EC50=25.1 microM), while ISO-0 did not react with DPPH. The scavenging capacity for superoxide enzymatically generated in a hypoxanthin-xanthinoxidase reaction was the highest for ISO-4 (EC50=34.3 microM) compared to those of ISO-3 (EC50=84.0 microM) and ISO-2 (EC50=91.8 microM), while ISO-0 was inactive. In analogy, ISO-4 scavenged peroxynitrite (ONOO-, EC25=23.0 microM) more effective than ISO-3, ISO-2 and ISO-0.When C6 rat glioma cells loaded with the reactive oxygen/nitrogen (ROS/RNS)-sensitive fluorochrome 2,7-dichlorodihydrofluorescein, were exposed to hydrogen peroxide, the lowest stress level as indicated by the fluorescence signal was detected when the cells were pretreated with ISO-4 or ISO-2 but to a much lesser extent with ISO-3, while ISO-0 did not show any effect. All tested hydroxyisochromans superceded the scavenging effect of trolox.The excellent radical and ROS/RNS scavenging features of the hydroxy-1-aryl isochromans and their simple synthesis let these compounds appear to be interesting candidates for pharmaceutical interventions that protect against the deleterious action of ROS/RNS.     

Novel pan-neuronal Cre-transgenic line for conditional ablation of genes in the nervous system

Tissue-specific gene ablation is accomplished by combining conventional gene targeting approaches with site-specific recombinases such as the Cre/loxP system. Despite the use of a cardiac-specific rat myosin light chain II promoter, our transgenic line (CRE3) had little or no Cre expression in the heart; however, strong Cre activity was detected in the brain as early as gestation day E11.5. This was determined by several methods including crossing our mouse line with a lacZ indicator line (ROSA26). Transgenic Cre, in this mouse line, mediated DNA recombination of loxP-flanked genes selectively in neurons throughout the gray matter of the brain, cerebellum, spinal cord, as well as retina, dorsal, and sympathetic ganglia. Cre protein was also detected by immunohistochemistry exclusively in neurons, but not in other types of cells or tissues. Thus, our transgenic CRE3 mice provide pan-neuronal expression of CRE for carrying out conditional deletion of genes in neurons and their progenitors.     

Maternal inheritance, sexual conflict and the maladapted male

Females differ from males in transmitting not only nuclear genes but also cytoplasmic genetic elements (CGEs), including DNA in mitochondria, chloroplasts and microorganisms that are present in the cell. Until recently, evolutionary research has adopted a nucleocentric approach in which organelles have been viewed as subservient energy suppliers. In this article, we propose that a more equitable view of nuclear genes and organelle genomes will lead to a better understanding of the dynamics of sexual selection and the constraints on male adaptation. Maternal inheritance of CGEs intensifies sexually-antagonistic coevolution and provides a parsimonious explanation for the relatively high frequency in males of such apparently maladaptive traits as infertility, homosexuality and baldness.     

Current understanding of the regulation of methionine biosynthesis in plants

Plants can provide most of the nutrients for the human diet. However, the major crops are often deficient in some of the nutrients. Thus, malnutrition, with respect to micronutrients such as vitamin A, iron, and zinc, but also macronutrients such as the essential amino acids lysine and methionine, affects more than 40% of the world's population. Recent advances in molecular biology, but also the grasp of biochemical pathways, metabolic fluxes, and networks can now be exploited to produce crops enhanced in key nutrients to increase the nutritional value of plant-derived foods and feeds. Some of the predictions appear to be accurate, while others not, reflecting the fact that plant metabolism is more complex than presently understood. A good example for a complex regulation is the methionine biosynthetic pathway in plants. The nutritional importance of Met and cysteine has motivated extensive studies of their roles in plant molecular physiology, especially regarding to their transport, synthesis, and accumulation in plants. Recent studies have demonstrated that Met metabolism is regulated differently in various plant species.